They come with a rubber stopper/cork which is better than the corks made out of 'cork' material that can wear away/crumble. I have done the bottle and sand project with classes for years using screw-on lids, corks, and these rubber stoppers. These are great for the money. The corks were hard to grab and remove when students found out they had to top off the sand levels. Obviously, the screw tops are the most child-friendly, but they are also the most expensive.
Date published: 2017-08-05